US2938262A - Process for the cold reduction of strip metal - Google Patents

Description

United States Patent THE COLD REDUCTION OF srmr METAL No Drawing. Filed July 25, 1958, Ser. No. 750,849

5 Claims. (Cl. 29424) PROCESS FOR This invention relates to improvements in the process for cold reduction of strip metal. In particular, it relates to a method for improving lubrication of pickled metal strip at the end of the pickling line just prior to recoiling and cold rolling. It also relates to a method for improving lubrication on the mill during the cold reducing process. Although this invention is applicable to the cold reduction of all metals, both ferrous andnonferrous, it is of particular utility in the cold reduction of steel.

It is an object of the present invention to eliminate friction scratches originating at the recoiler. It is a further object of this invention to obtain good shape of the strip during the process of cold reduction by means of improved lubrication; In particular, it is an object of the present invention to provide a method for operating cold reducing mills, specifically steel mills, at higher speeds because of improved lubrication between the strip and the rolls. Other objects of this invention will be apparent as hereinafter set forth. I It is well known that modern cold mill construction permits the attainment of speeds up to and in excess of 5000 feet per minute on the delivery end of the mill. In some cases, new mills are rated as high as 6500 feet per minute. In spite of these high ratings, however, it has been found impossible to operate these mills at such speeds because of inadequate lubrication of the strip as it passes betweenthe reducing rolls. It is particularly desirable to attain the highest possible speeds in order to insure maximum output when rolling blackplate or tinplate, i.e. strip ranging in final thickness down to about in the order of 0.008 inch. Palm oil is the material most commonly employed as lubricant in current industrial-practice for rolling tinplate gauges, but with this material it is not practicable to attain speeds much in excess of 4000 feetper minute for any length of time even on mills rated at much higher speeds. Overload or friction scratches, poor shape, breaks, and other troubles well known to steel mills occur when higher speeds are attempted with palm oil or with any other rolling lubricant which has been used up until the present invention.

We have now found that speeds varying from several hundred to over a thousand feet per minute greater than those obtainable with palm oil can be attained and main- ,tained over protracted periods by. utilizing as rolling. lubricant, otherwise known as rolling oil, processed fats and fatty oils or mixtures thereof of animal or vegetable in the case of oils which do not gel under such prolonged conditions of heating. It will normally not be less than six hours. I

In general, we may use any fat or fatty oil of animal 'or vegetable origin comprising essentially non-drying or semi-drying'components. We prefer to use fats or oils which are largely saturated or mono-olefinic in the structure of their component fatty acids, in particular those fats and oils which are edible such, for example, as lard, hydrogenated fats and oils like Criscoa product manufactured by Procter and Gamble Company, corn oil, peanut oil, or blends of cottonseed and corn oil which may or may not be hydrogenated such, for example, as that available under the trademark Yolanda (CIF. Simonins Co., Inc., Phila., Pa.). We prefer to use fatty, semi-solid heat processed edible fats, oils, and greases which may or may not be reclaimed. We may however, use any heat-processed fat or oil of non-drying or semidrying nature. Reclamation will usually consist essentially of melting if necessary, straining and/or settling insoluble solid matter in such manner that the fatty material is freed of extraneous non-fatty solid material and substantially freed of moisture. The reclamation process may be carried out simply by blending available melted fats, oils and greases and straining the blend through grates or perforated plates, then transferring to settling vats where it is further heated to establish homogeneity and drive off water before collection in storage tanks. Reclamation may also be carried out by treatment with live steam, filtration, and settling. Other procedures may be employed for the same purpose and the final product may, if desired, be washed with brine or alum solution in order to clarify it and aid in removal of water. Such reclamation processes are well known to the fat rendering industry. In all cases, the fat, oil or grease reclaimed will have been heatprocessed as hereinbefore stated prior to reclamation.

Although the chemical literature is replete with the results of theoretical investigations which have been undertaken to learn the nature of chemical reactions which occur during the heat treatment of various fats and oils, we are not able to identify the remarkable improvements in rolling properties effected by this heat treatment with any specific chemical changes. One of the most apparent physical changes occurringduring this processing is the increase of viscosity. Thus, samples of eight different types of fats, oils, and greases were subjected to heat in a stainless steel beaker at 300 F. to 350 F. for 24 hours. Samples were removed at the end of 12 hours and 24 hours, and compared in viscosity with the original products before heating with the results given in the following table:

Viscosity of heated fats and oils at F.

'(Saybolt Universal seconds) While a considerable degree of latitude is permissible in the viscosity of heat-processed oils used according to our present invention, it will generally run between from about 200 to about 500 Saybolt Universal seconds at.

100 F., the preferred range being 230 to 320. Although useful products may be liquid at room temperature, we prefer to employ heat-processed fats, oils, and greases having a pour-point ranging from about F. to about 85 F., preferably from 55 F. to 50 F.

When examined for frictional properties by means of the Falex machine (U.S. Patents 2,106,170 and 2,110,- 2 88) modified so as to measure torque in gram centimeters, using a lever approximately 20. inches in length, a representative sample of heat-processed fat having an acid number of 12, a saponification number of 200, and a titre of 40 C., showed a torque of 10,150;gram-centimeters. In contrast to this value, a typical sample of palm oil tested at the same time gave a torque of 12,600 gramcentimeters, i.e., a value 24% greater.

The rolling oil used in accordance with the process of this invention, i.e., heat-processed fatty oil or grease, may be applied to the cold reduction of steel according to any of the well-known current steel mill practices in place of palm oil or its equivalent. Thus, it may be used in the so-called direct application method or, in conjunction with an emulsifier, if desired, in recirculating systems. It may be used on either single stand or tandem mills, or on reversing mills.

In a typical run on a five stand tandem mill, the rolling oil of this invention was stored in storage tanks at 150 F. and mixed with Water at the same temperature by means of proportioning pumps through which it was fed and supplied to the mill rolls. It was used at a ratio of about one part of oil to ten parts of water in, the first three stands and at a ratio of about one part of oil to eight parts of water at the last two stands. This corresponds to average mill practice although, at. times, the ratio of premixed water and rolling oil may run between the approximate extreme limits of 1:1 and 20:1. The strip was cooled in the customary manner while passing through the mill by flooding with water. The hot rolled band to be cold reduced was coated at the pickler oiler with the same oil of this invention and coiled befo're being fed through the tandem mill. Band rangingin initial gauge from 0.079 to 0.082 inch in thickness was reduced to a finished gauge ranging from 0.0083 to 0.0098 inch.

Approximately 500,000 lbs. of steel was cold reduced in this run, with speeds of 5500 feet per minute being attained. In general, in order to maintain friction scratches at a minimum, it was found advisable to operate at 5000 feet per minute which speed was maintained continuously during several hours. These speeds were several hundred feet per minute faster than could be attained with palm oil on the same mill. Reduction on the mill was excellent, as was surface appearance and shape. The sheet so produced was subsequently annealed, cleaned, and tinned-half by electrolytic tinning, half by hot dipping, using conventional methods. The tinplate thus produced was of prime quality. In another run on the same mill, carried out in a manner similar to that just described, forty coils of steel having a tinplate gauge of 0.0087 inch was reduced from hot band of 0.080 inch thickness at a speed of 4500 feet per minute. This speed compares with a maximum speed previously obtainable with palm oil on the same mill, with the same steel and similar reductions, of 3500 feet per minute.

it is thus evident that the process of our invention, utilizing heat-processed non-drying and semi-drying fats, oils, and greases as a coating oil for application at the "pickler oiler and as a rolling oil on the cold reduction mill atfo'rds a means of efiecting substantial economies in the manufacture of strip steel.

It is to be understood that the essential lubricant of this invention, i.e. heat-processed fats and fatty oils of non-drying or semi-drying nature, may, if desired, be compounded with other materials 'known to the lubricating art, such as other fats and fatty oils which have not been heat-processed, mineral oils, extreme pressure additives emulsifying agents and the like.

We claim:

1. In a process of cold reduction of strip metal, the step which comprises coating the metal prior to passing. same between reducing rolls with a rolling oil containing a lubricant selected from the group consisting of fats, oils and greases of non-drying and semi-drying characteristics heat treated at a temperature ranging from about 200 F. to about 500 F. from about 6 to about 72 hours and having a viscosity of from about 200 to about 500 Saybolt Universal seconds at 100 F. and a pour point from about 0 F. to about 85 F., said lubricant being stable at high cold metal reduction speeds.

2. In a process of cold reductio'n of strip metal, the step which comprises coating the metal prior to passing same between reducing rolls with a rolling oil containing a lubricant selected from the group consisting of fats, oils and greases of non-drying and semi-drying characteristics heat treated at a temperature ranging from 250 F. to 450 F. from about 6 to about 72 hours and having a viscosity of from about 200 to about 500 Saybolt Universal seconds at 100 F. and a pour point from about 0 F. to about 85 F., said lubricant being stable at high cold metal reduction speeds.

3. In a process of cold reduction of strip metal, the step which comprises coating the metal prior to passing same between reducing rolls with a rolling oil containing a lubricant selected from the group consisting of fats, oils and greases of non-drying and semi-drying characteristics heat treated at a temperature ranging from 300 F. to 350 F. from about 6 to about 72 hours and havinga viscosity of from about 200 to about 500 Saybolt Universal seconds at 100 F. and a pour point from about 0 E. to about 85 F., said lubricant being stable at high cold metal reduction speeds.

4. In a process of cold reductio'n of strip metal, the step which comprises coating the metal prior to passing same between reducing rolls with a rolling oil containing a lubricant selected from the group consisting of fats, oils and greases of non-drying and semi-drying characteristics heat treated at a temperature ranging from 300 F. to 350 F. and having a viscosity of from about 200 to about 500 Saybolt Universal seconds at 100 F. and a pour point from 50 F. to F.

5. In a process of cold reduction of strip metal, the step which comprises coating the metal prior to passing same between reducing rolls with a rolling oil containing a lubricant selected from the group consisting of fats, oils and greases of non-drying and semi-drying characteristics heat treated at a temperature ranging from 300. F. to 350 F. and having a viscosity of from 230 to 320 Saybolt Universal seconds at F. and a pour point from 50 F. to 70 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,383,906 Zimmer Aug. 28, 1946 2,413,121 Swenson Dec. 24, 1946 2,486,130 Dietrich Oct.- 25, 1949 2,588,625 Ferner, Mar. 11, 1952 2,590,451 Perry 2 Mar. 25, I952 UNITED STATES, PATENT OFFICE GERTIFICATE or CORRECTION Patent No, 2,938 262 May 31, 1960 t George E. Barker et alu It is hereby certified that error appears in the printed specification of the above number-ed patent. requiring correction and that the. said Letters Patent should read as corrected belowa Column 4 lines 50 and 59 after "70 F3, each occurrence,

insert said lubricant being stable at highcold metal reduction speeds Signed and sealed this 22nd day of November 1960.

(SEAL) Attest:

KARL H, AXLINE ROBERT c. WATSON, Attesting Officer I Conmissioner of Patents

Claims (1)

1. IN A PROCESS OF COLD REDUCTION OF STRIP METAL, THE STEP, WHICH COMPRISES COATING THE METAL PRIOR TO PASSING SAME BETWEEN REDUCING ROLLS WITH A ROLLING OIL CONTAINING A LUBRICANT SELECTED FROM THE GROUP CONSISTING OF FATS, OILS AND GREASES OF NON-DRYING AND SEMI-DRYING CHARACTERISTICS HEAT TREATED AT A TEMPERATURE RANGING FROM ABOUT 200*F. TO ABOUT 500*F. FROM ABOUT 6 TO ABOUT 72 HOURS AND HAVING A VISCOSITY OF FROM ABOUT 200 TO ABOUT 500 SAYBOLT UNIVERSAL SECONDS AT 100*F. AND A POUR POINT FROM ABOUT 0*F. TO ABOUT 85*F., SAID LUBRICANT BEING STABLE AT HIGH COLD METAL REDUCTION SPEEDS.